Textile materials resistant to fading



3,021,188 TEXTHJE MAT" RlALS RESXSTANT T8 FADLJG Anthony BernardConciatori, Chat'ham, NHL assignor to Celanese Corporation of America,New Yerlt, N.Y., a corporation of Delaware No Drawing. Filed .lan. 24,1958, Ser. No. 710,876 (Ilaims. ((31. 8-61) This application is acontinuation-in-part of my copending application Serial Number 534,396,filed September 14, 1955, now abandoned.

This invention relates to dyed materials and relates more particularlyto dyed organic derivative of cellulose textile materials.

The art is well acquainted with the problem of the gasfading, which isalso called acid-fading, of dyed textile material having a basis of anorganic derivative of cellulose. Such gas-fading may cause a materialcolored with a blue anthraquinone dye to take on a reddish hue, forexample. It is generally accepted that this type of fading results fromthe presence in the atmosphere of certain oxides of nitrogen, whichoxides are produced during combustion of coal, gas or other fuels. Tocombat this type of fading, inhibitors comprising basic nitrogencompounds, e.g. amines, are often incorporated into the textilematerial, before, during, or after the dyeing thereof.

On exposure to elevated temperatures the amine-type inhibitors show atendency to discolor the textile material. This discoloration. isparticularly noticeable where the textile material to which theinhibitor is applied has a basis of a cellulose ester of low hydroxylcontent, since such textile materials are generally exposed duringprocessing to much higher temperatures than are employed for textilematerials made from other cellulose derivatives. For example, textilematerials of cellulose acetate of low hydroxyl content, commonly knownas cellulose triacetate, are usually subjected to a heat-treatingoperation during which the fabric temperature may reach 250 C. Alsoheat-treated cellulose triacetate textile materials have very high safeironing points, on'the order of 240 C. or higher, and they are thereforeironed at temperatures which are much higher than those which could beemployed in the case of ordinary cellulose acetate. Both theheattreating operation and the high temperature result in somediscoloration of the textile material when an amine-type gas-fadinginhibitor is present. Thus, although the discoloration caused byheat-treating may be removed by the application of bleaching agents tothe material, it tends to return when the material is subsequentlypressed with a hot iron.

When the amine-type gas-fading inhibitor are omitted, or when there areemployed selected inhibitors of this type which exhibit a greatlydecreased tendency to discolor on heating, 1 have observed another typeof fading of the anthraquinone dyes on the textile material, even whenthe material is not exposed to atmospheric oxides of nitrogen to anysubstantial extent. This type of fading called O-fading, I believe to bedue to oxidative substances present in the atmosphere which react withthe dye in the material. It is observed even on organic derivative ofcellulose textile materials colored with those dyestutfs which normallyhave very high resistance to gas-fading, such as the blue dyestuff,1,8-dihydroxy-4-p- (beta-hydroxyethyl)anilido-S-nitroanthraquinone. Inthe case of the cellulose esters of low hydroxyl content, the O-fadingof the colored material is particularly noticeable where the coloredmaterial is exposed to an atmosphere containing the aforesaid oxidativesubstances before the colored material has been heat-treated. This maytake place when a fabric is dyed and then stored before heattreating.

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Although O-fading is prevented to a large extent by the incorporation ofthe usual amine-type gas-fading inhibitors in the textile material,these inhibitors, as pointed out above, cause undesired discoloration onheating. Other disadvantages of the amine-type inhibitors are that theygenerally tend to decrease the light-fastness of the dyed material andincrease the tendency of dyed material to pick up chlorine when thematerial is washed in an aqueous medium containing the usual bleachingagent comprising sodium hypochlorite. Also, they usually make thematerial more receptive to acid dye, thus making it difiicult to obtaincross-dyed effects in fabrics comprising the organic derivative ofcellulose and an animal fiber such as wool.

It is therefore an object of this invention to provide a novel textilematerial, having a basis of an organic derivative of cellulose whichmaterial is free from the foregoing and other disadvantages.

Another object of this invention is the provision of an organicderivative of cellulose textile material which,

when dyed with anthraquinone dyes, is resistant to O-fading and Will notdiscolor a textile.

It is a further object of this invention to provide a textile materialof cellulose triacetate having incorporated therein a wash-fastinhibitor of O-fading.

Other objects of this invention Will be apparent from the followingdetailed description and claims. In this description and claims allproportions are by weight unless otherwise indicated.

In accordance with one aspect of this invention it has been found that'O-fading is inhibited by the presence in the organic derivative ofcellulose textile material of aliphatic carbon-to-carbon unsaturation ofa non-conjugated nature, i.e. isolated ethylenic or acetylenic bonds.

This invention finds its greatest utility When the organic derivative ofcellulose is a cellulose ester of low hydroxyl content, since, aspointed out above, in the normal treatment and use of such celluloseesters the elevated temperatures employed will generally tend todiscolor the usual basic nitrogenous gas fading inhibitors. Thesecellulose esters contain not above 0.29, preferably 0 to 0.12, hydroxylgroups per anhydroglucose unit in the cellulose molecules thereof. Theinvention is also applicable, however, to organic derivatives ofcellulose having a higher hydroxyl content, e.g. ripened, secondary orpartially esterified cellulose.

The carbon-to-carbon unsaturation may be present in the organicderivative of cellulose molecule which comprises the textile material bybeing bound to the anhydroglucose units through their oxygen atoms, e.g.a cellulose acetate crotonate yarn having a low free hydroxyl contentand a few percent of crotonyl groups can be heat treated and dyed withnormally O-fading susceptible dyes without change in color. Preferably,however, the carbon-to-carbon unsaturation is present in a substancewhich is added to the organic derivative of cellulose in any suitablemanner before, during or after the dyeing thereof. Advantageously it isincorporated into the organic derivative or cellulose before the latteris formed into filaments. To this end the inhibitor may be added to thespinning dope, e.g. to a solution of cellulose triacetate in a methylenechloride-containing solvent, for example, a solvent comprising methylenechloride alone or admixed with a lower alkano l such as methanol,ethanol, propanol, isopropanol, or butanol or mixtures of such alkanols.However, the inhibitor may also be applied in the form of a solution oran aqueous dispersion thereof, to the organic derivative of celluloseafter it has been formed into filaments, especially where the inhibitorwould be only slightly soluble in the spinning dope, e.g.dimethallylidene pentaerythritol which has limited solubility inmethylene chloride.

To produce a satisfactory degree of O-fading inhibition there should bepresent at -least one unsaturation per 50' anhydroglucose units andpreferably at least one per 30- anhydroglucose units of the organicderivative of cellulose. be achieved by using as the filamentarymaterial a cellulosederivative which is inherently an inhibitor ofO-fading due to the presence of unsaturations, i.e. a cellulosederivative wherein some of the cellulose hydroxyl groups are esterifiedor etherified with unsaturated acids or alcohols, e.g. cellulosemethallylsuccinate, allyl ether of cellulose acetate, methallyl ether ofcellulose acetate propionate, and the like.

Advantageously, however, the O-fadinig inhibition is achieved by addingunsaturated substances to a cellulose. ester of a lower alkanoic acid.Representative unsaturated additives which can be used in accordancewith the present invention include diallyl phthalate, diallyl succinate, acrylic or crotonic acid esters of monoor polyhydric alcohols orunsaturated polyesters of p'olyhydric alcohols and polycarboxylic acids.Examples of such unsaturated polyesters are the linear esters of suchsaturated glycols as ethylene glycol, 1,2-propylene glycol,

'trimethylene glycol, 1,4-but'ene diol, isobutylene glycol ortetramethylene glycol with such unsaturated acids as allyl succinicacid, methallyl succinic acid and itaconic acid. The unsaturatedpolyesters may also be formed from unsaturated glycols such as1-allyloxy-2,3-propanediol, butcnediol and butyne diol and apolycarboxylic acid which may be unsaturated, e.g. the polyester ofbutyne diol and methallyl succinic anhydride, or saturated, e.-g. thepolyester of butyne diol and succinic anhydride.

Other types of unsaturated organic compounds may also be employed. Forexample, a highly crotonate'd cellulose acetate crotonate can be addedto cellulose acetate to bring the average degree of unsaturation Withinthe recited ranges. Allyl cellulose and other ethers or esters with ahigh degree of tunsaturation can be similarly employed. There may alsobe used unsaturated hydrocarbons which are compatible with the organicderivative of cellulose in the amounts present. Examples of suchhydrocarbons are the liquid homopolymers of butadiene and the liquidcopolymers of butadiene and styrene (e.g. the product known as C-oil).Unsaturated ethers and acetals can also be employed, e;g. di-acro-leinacetal of pentaerythritol (dicrotonylidene pentaerythritol), triallylcyanurate, and the like. While trial'lyl cyanurate contains nitrogenatoms, the compound is not basic since the nitrogen of the triaziue ringis not basic and does not result in the color change occasioned byconventional basic nitrogenous gas-fading inhibitors. Those additivesare preferred which have relatively high molecular weights, e.g. atleast 100 and preferably above 500. Such compounds have greater fastnessto washing and will not be lost through vaporization duringheat-treating. The unsaturation of the inhibiting group should benon-conjugated, i.e. isolated, and is preferably in a short pendantbranch rather than in the main chain of the inhibiting compound, sincesuperior O-fading is thereby achieved. While polyesters having higheracid numbers give better O-fading resistance, they render processingsomewhat more diflicu-lt so that additives of lower acid numbers arepreferred,

The preferred additives are non-volatile linear polyesters of molecularweights of at least about 500, possessing non-conjugated unsaturationsin short side chains, and having acid numbers below about 50.

The proportion of unsaturated additive employed is desirably in therange of about 1 to 10% by weight of the cellulose derivative.preferably about 1 to 3%. Advantageously, there should not be used anamount of the inhibitor larger than that which is compatible with theorganic derivative of cellulose or an amount sufiicient to changeappreciably the physical properties of said onganic derivative ofcellulose.

As noted previously, this level of unsaturation can As noted previously,best results are obtained when the ester to which the inhibitor is addedis a cellulose acetate of very high acetyl value, preferably of acetylvalue 61 to 62.5%, calculated as combined acetic acid. However, otherorganic acid esters of low hydroxyl content may be employed. Examples ofsuch other esters are cellulose propionate, cellulose butyrate,cellulose acetate-propionate, cellulose acetate-butyrate and celluloseacetate-formate. It is to be understood, of course, that the unsaturatedO-fading inhibitors may also be incorporated into textile materialshaving a basis of other organic derivatives of cellulose such as thosecellulose esters of higher hydroxyl content, e.g. cellulose acetate ofacetyl value 53 to 56%, calculated as combined acetic acid.

The coloring of the textile material may be carried out in a manner wellknown to the art, preferably by applying one or more dyestuffs of thetype known as dispersed cellulose acetate dyestuffs. Thus, the materialmay be immersed in a heated aqueous bath having a temperature of, forexample, 60 to 95 C. and containing one or more dispersed celluloseacetate dyestuffs together with a dispersing agent therefor, such assodium lignosulfonate, sulfonated naphthalene-formaldehyde condensationproduct or soap. Practically any desired hue may be imparted to thematerial by the use of appropriate mixtures of dyestuffs, as by usingmixtures of varying amounts of red, blue and yellow dyestuffs.

Preferably the blue dyestuff used is of the type which is highlyresistant to gas-fading. This type of dyestutf may be described as thosewhich show negligible fading when applied in the amount of 0.3% based onthe fabric weight and in the absence of a gas-fading inhibitor toa'textile fabric of cellulose acetate of acetyl value 61.5%, andsubjected to 3 units of gas-fading exposure in accordance with TestMethod 23-52 as given in the Technical Manual and Yearbook of theAmerican Association of Textile Chemists and Colorists 1954, page 87.Specific examples of such dyestuifs are 1,8-dihydroxyp (betahydroxyethyl) anilido 5 nitroanthraquinone;1-hydroxy-4-anilido-anthraquinone; 1,8-dihydroxy- 4 m (alphahydroxyethyl) anilido 5 nitroanthraquinone.

"When an aqueous dyebath is employed, the rate of dyeing may beincreased by the use of a suitable dyeing assistant, e.g. pine oil,tripropyl phosphate, tributyl phosphata diethyl phthalate, methylsalicylate or an N,N-dihydroxyethyl fatty acid amide, such asN,N-dihydroxyethyl capramide. Such dyeing assistants may be applied tothe material, as by padding, before dyeing or may be added to thedyebath. As stated, the ethylenically unsaturated O-fading inhibitor mayalso be applied to the textile material during the dyeing thereof. Tothis end the inhibitor may be dispersed in the aqueous dyebath ifdesired.

Instead of immersing the textile material in a heated aqueous dyebaththe textile material may be colored by applying thereto a printing pastecontaining the desired dyestuffs. Alternatively the textile material maybe colored by passing it through a heated solution of the dyestuff in aliquid polyhydric alcohol such as ethylene glycol. Any other coloringmethods known to the art may be employed.

As stated, the textile material having a basis of a cellulose ester oflow hydroxyl content is given a heat-treatment, preferably during orafter the application of the coloring material thereto. This treatmentserves to increase the penetration of the dye into the cellulose esterand increases the wa'sh-fastness, resistance to gas-fading, resistance.to orfading and resistance to crocking of the dyed material.Heat-treatment also effects an improvement in the physical properties ofthe textile material. Thus, it effects an improvement in the safeironing temperature, its resistance to glazing, its resistance toshrinkage on pressing with moist steam, its resistance to mussing orwrinkling on laundering, its resistance todegt'adafor returningvaporized glycol to the mixture.

53 tion or weakening on exposure to elevated temperatures for longperiods of time and its resistance to degradation in sunlight. Forexample, heat-treatment of a fabric of cellulose acetate of low hydroxylcontent raises its safe ironing temperature by at least about 20 C.,e.g. up to 220 C. or higher. Heat-treatment generally results in anincrease in the crystallinity and crystalline order index of thecellulose ester material.

The conditions of heat-treatment will depend somewhat on the particulartextile material being treated, for example, on its Weight andconstruction. In general, when dry heat is used, as when the textilematerial is passed through a hot air heater, an infra-red heater or incontact with heated rollers or drums, temperatures of 190 C. or aboveare employed. Preferably, the material is heated to a temperature ofabout 220 to 235 .C. for about 7 to 30 seconds. With lower temperatures,e.g. 190 C., the heating time is considerably longer, for example tominutes. Still lower heat-treatment temperatures may be employed whenthe heat is applied by means of saturated steam under a pressure of forexample to 40 pounds per square inch or by means of a heated bath ofethylene glycol or other polyhydric alcohol. The coloring andheat-treatment may be combined, as by subjecting the textile materialfor a sufficient period of time to a suitable liquid medium containing adyestuff dispersed or dissolved therein. For example, the material maybe dyed and heat-treated in an aqueous medium maintained undersuperatmospheric pressure at a temperature of 90 C. or above or in asolution of the dyestuff in hot ethylene glycol. The termheat-treatment" as employed herein accordingly has reference to hightemperature, and the like, as well as treatments at moderatetemperatures with solvents or assistants to achieve similarimprovements.

If desired, the unsaturated O-fading inhibitors of this invention may beused in combination with amine-type gas-fading inhibitors. In this casethe amount and type of amine should be such that there is littlediscoloration pending application and 1% of an unsaturated polyestercombined by the reaction of methallyl succinic anhydride and glycol.When the amine-type inhibitor is present discoloration may be reduced bysubjecting the textile material to a bleaching agent, after, orpreferably before, the heat-treatment operation. 7

The following examples are given to illustrate this invention further:

Example I A mixture of 1 mole of methallyl succinic anhydride and 1.1moles of ethylene glycol is heated and stirred under nitrogen atmospherefor 5 hours, on an oil bath kept at 200 C., in a vessel equipped with acondenser The resulting polyester, which has an acid number of 16 or 17,is purified by dissolving it in a mixture of 90% of methylene chlorideand 10% of methanol and boiling the resulting solution in the presenceof charcoal.

Example 11 To a spinning solution containing 21 parts of celluloseacetate of 61.5% acetyl value, in 79 parts ofa mixture of 90% ofmethylene chloride and 10% of methanol 7 there is added 0.63 part of thepurified polyester produced in Example I. The solution is spun into yarnand woven into a fabric, which is then dyed withl-methylamin'o-4-hydroxy-ethylamino-anthraquinone and there- Thus, theremay 'sponding to 4 on the International Gray Scale, after hours of thefading exposure. When the above example is repeated, except that thematerial of Example I is I omitted the dyed and heat-treated fabricshows a shade change corresponding to a rating of only 2-3 after 100hours of fading exposure. In neither case does the heattreatment, or asubsequent heating for 15 minutes at 200 C., cause any appreciablediscoloration of the fabric. Also, both the material containing theunsaturated polyester of Example I and the material containing none ofthis polyester were equally unaffected by acid dyes under standardwool-dyeing conditions, showing that they could be used for producingcross-dyed efiects in wool blends.

When the fabric of this example is tested for O-fading before theheat-treatment it shows no shade change whatever (a rating of 5) after18 hours of fading exposure and shows a slight change, corresponding toa rating of 3-4 after 100 hours. The corresponding figures for thefabric containing none of the unsaturated polyester of Example I are 3-4and 1-2 respectively.

Example III A mixture of 1 mole of methallyl succinic anhydride and 1.05moles of ethylene glycol is heated and stirred under nitrogen atmospherefor 2 hours, on an oil bath kept at C., in a vessel equipped with areflux condenser for returning vaporized glycol to the mixture andwithdrawing water of condensation. The temperature is raised to 210-220C. for 5 hours longer, the pressure is reduced to 190 mm. Hg and heatingis continued for 3 hours. The resulting polyester, which has an acidnumber of 3.0 and a molecular weight of about 1000, is purified bydissolving it in a mixture of 90% by weightof methylene chloride and 10%by weight of methanol and boiling the resulting solution in the presenceof charcoal.

Example IV To a spinning solution containing 21 parts of celluloseacetate of 61.5% acetyl value, in 79 parts of a mixture of 90% ofmethylene chloride and 10% of methanol there is added 0.63 part of thepurified polyester produced in Example 1H (1 methallyl groupunsaturation for 23 anhydroglucose units) and .01 part of InterchemicalBlue B dyestuff, ie a mixture of 1,4-bis-methylaminoanthraquinone and1-methylamino-4-beta-hydroxyethylamino-anthraquinone. The solution isspun into yarn and woven into a fabric, which is then scoured for 10minutes at 40 C. in a bath containing 1 gram/liter of soap and 1 gram/liter of sodium lrexametaphosphate. The scoured fabric is exposed to anO-fading atmosphere for 70 hours and the color is compared with thatbefore exposure. The comparison is made with the Hunter Color DifferenceMeter which measures the L (grayness), a (redness or greenness) and b(yellow or blueness) of the sample. The number of units of color changeAB is determined according to the following equation:

The color change is only 5.2 units as compared with 15.3 for a controlfabric similarly treated but containing no O-fading inhibitor.

The fabric of this example is about as resistant to gasfading andultraviolet light as the control containing no O-fading inhibitor. Thepresence of the inhibitor does not change the lack of affinityof theyarn for acid dyes v under standard wool-dyeing conditions, showing thatthe 75' inhibitor-containing "yarn could' be used for producingcross-dyed effects in wool blends. On storage, the viscositycharacteristics of the inhibitor-containing dope are the same as thosefor the dope from which the control fabric is prepared.

Example V (a) Cellulose acetate of 61.5% acetyl value is dissolved toform a 21% by weight solution in a 90-10 weight mixture of methylenechloride-methanol. The solution is divided into a test specimen and acontrol specimen there being added to the test specimen 3% by weight ofthe polyester of Example III, based on the cellulose acetate. Bothsolutions are spun to form filament yarns and the yarns are each Woveninto fabrics. An inhibitor-containing fabric sample and aninhibitor-free fabric sample are prescoured at 180 F. for one hour in0.5 gram per liter of soap.

(b) Inhibitor-containing and inhibitor-free scoured and unscouredsamples are then dyed with 0.05% by weight of. the dyestuffl,8-dihydroxy-4-p-(beta-hydroxyethyl)- anilido-S-nitroanthraquinone andtested to determine the extent of O-fading after 40 hours exposure to anO-fading atmosphere. The fabrics containing no inhibitor undergo severeshade changes (a rating of 2) whether or not prescoured. Theinhibitor-containing fabric which is not prescoured undergoes a veryslight shade change (4-5) while the inhibitor-containing fabric which isprescoured undergoes a slight to moderate change (34).

This indicates that the inhibitor is resistant to removal by scouringand during dyeing.

Samples of unscoured inhibitor-containing and inhibititor-free fabricsas produced in (a) are dyed for two hours at 176 F. with Eastone RedGLF, i.e. 2- methylsulfone 4 nitro 4' (N hydroxyethyl N-beta-difluoroethyl)-amino-azobcnzene. Where the fabric is inhibitor-freeits dye content is found to be 0.52% whereas the inhibitor-containingfabric picks up 0.73% of dyestuff, indicating that the inhibitor acts asa dyeing accelerant. The washfastness of the fabrics are equal.

Example VI A mixture of 1 mole of methallyl succiuic anhydride and 1.05moles of ethylene glycol is stirred with an equal weight of xylene undernitrogen atmosphere and heated to reflux using a system to condense andseparate water vapor while returning xylene. After the theoreticalquantity of water is collected, i.e. in about 4 hours, refluxing iscontinued for an additional 3 hours. The xylene is then distilled offand the temperature is raised slowly to 200 C. While the pressure isreduced to 5 mm. Hg and held for 20 minutes. After cooling, thepolyester is purified as in Example III. Its acid number is 113.0 andits molecular weight is about 1000. It is incorporated into a spinningdope along with dye, spun, and tested as in Example IV. The dyedmaterial after 70 hours exposure to an O-fading atmosphere undergoesacolor change AE of 3.7 units.

Example VII Allyloxypropanediol is substituted for the glycol in ExampleIII to give a product with an acid number of 9.8 and a molecular weightof 850. The ester is incorpo rated into a spinning dope which is treatedas in Example IV. The color change AE after 70 hours of O-fading is 3.1.

Example IX The linear polyester of maleic anhydride and butene diol,prepared in the same manner as the polyester in,-

'held for 10 minutes.

Example VI and having an acid number of 5.2 and a molecular weight of1307, is used in repeating the process of Example IV. The color changeAli is 5 .5 units after 70 hours of O-fading.

Example X Succinic anhydride and butene diol are substituted for theanhydride and glycol in the process of Example VI and the resultingpolyester exhibits an acid number of 1.6 and a molecular weight of 1300.It is used in repeating the process of Example IV and after 70 hoursO-fading the fabric. undergoes a color change 31E of 5.6 units.

Example XI A mixed cellulose acetate crotonate having a crotonyl valueof 46% and an acetyl value of 20.2% calculated as the combined acids, isprepared as follows:

parts by weight of cotton linters are shaken for 2 hours at roomtemperature with 35 parts of glacial acetic acid. The pretreatedlinters' are cooled to about 10-20" C., and 900 parts of methylenechloride and 400 parts of crotonic anhydride, cooled to 3-5 C., areadded. 1 part of perchloric acid is added and the temperature of themass, which is continuously stirred, starts to increase. A peaktemperature of 32-38 C. is reached in 20 minutes, and the vessel whichcontains the mass is immersed in ice water. Stirring is continued for 40minutes, at which time the mass becomes a clear amber colored dope. 700parts of methylene chloride are added, the perchloric acid isneutralized with a slight excess of ammonium hydroxide and the vessel istumbled for an additional hour. Boiling water is poured into smallvolumes of the dope causing ebullition of methylene chloride andprecipitation of the mixed ester. The mixed ester is washed free ofcrotouic acid and anhydride with ethanol and then with ether, and isdried first in air and then in an oven at 60 C. for 12 hours. The driedester is dissolved in a 90/10 weight mixture of methylenechloride/methanol and the solution is combined with a 21 weight percentsolution of cellulose triacetate in a 90/10 weight mixture of methylenechloride/ methanol. The proportion of cellulose acetate crotonatesolution added to the cellulose triacetate spinning dope is varied sothat in successive runs the weight percentage of the cellulose acetatecrotonate based on the cellulose triacetate is 3%, 4.5% and 10%. Thedyestuff employed in Example IV is added to the modified spinningsolutions and they are separately spun into filaments, beingaftertreated as in Example IV. ,The color change AE after 70 hours ofO-fading are respectively 5, 4 and 3 units.

Example XII Three parts by weight of cellulose are pretreated for 2hours with 35% by weight of glacial acetic acid. At 0 C. the celluloseis mixed with an esterification mix comprising 2.5 parts of aceticanhydride, 3.15 parts of acetic. acid, 0.82 part of crotonic acid, 0.68part of crotonic anhydride and'0.21 part of sulfuric acid. A peaktemperature of 45 C. is reached in minutes and The resulting dope ismixed with Water to precipitate the cellulose mixed ester, which iswashed with alcohol, ether and then dried. The ester has a crotonylcontent of 4.2% and an acetyl content of 57.7%, calculated as combinedacids, and has 0.09 free hydroxyl per anhydroglucose unit. The ester isdissolved, spun into yarn, and woven into a fabric which when subjectedto O-fading: for 70 hours undergoes a colorchange AE of.3.4 units.

Example XIII Dopes are prepared as in Example IV, substituting for theinhibitor there disclosed 3% based on the weight of the cellulosetriacetate of the following compounds: diethyl phthalate, diallylphthalate, diallylidene pentaei'ythritol, dicrotonylidenepentaerythritol, triallyl cyanurate, C-oil and the polyester of succinicanhydride and ethylene glycol. Fabrics prepared as in Example IV aretested for color change and the values are given in the following tablealong with those for fabrics produced in accordance with Examples IV andVI to XII.

Units Color Change After 70 Hours O-iading Wt. Percent on Cellulose'lrlacetate Diethyl phth alate Diallyl phthalate Diallylidenepentaerythritol. Dicrotonylidenepentaerytbrito ODIN WWW CD 09 he s was rExample IV Three liters of a dyebath containing 1.5 grams of sodiumN-rnethyl-oleyl-taurate, 1.5 grams of sodium hexametaphosphate and 0.09gram of the dyestuff of Example IV are heated to 95 C. The dyebath isdivided into three equal portions, a solution of 0.3 gram of diallylphthalate in 10 ml. of dioxane being stirred into one portion and asolution of 0.3 gram of triallyl cyanurate in 10 ml. of dioxane beingstirred into another portion. Identical 10 gram samples of cellulosetriacetate fabric are placed in each of the three dyebaths and removedafter 1 hour. The samples are rinsed thoroughly in lukewarm water anddried. Exposure of the fabrics to an oxidizing atmosphere shows that thedyed fabrics treated with the unsaturated additives are much moreresistant to color change than the control.

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that many variations may be madetherein without departing from the spirit of my invention.

Having described my invention, what I desire to secure by Letters Patentis:

l. A heat-treated material exhibiting a safe-ironing temperature of atleast 220 C. and having a basis of organic acid esterified cellulosecontaining at most 0.29 hydroxyl groups per anhydroglucose unit in thecellulose molecule thereof, there being present in said textile materialat least one isolated non-conjugated aliphatic carbon-to-carbonunsaturation per 50 anhydroglucose units for protecting said textilematerial against O-fading when said material is colored with ananthraquinone dye, said unsaturation being present in molecules free ofsaltforming groups.

2. A textile material dyed with a dye normally subject to O-fading, saidtextile material having a basis of organic acid esterified cellulosecontaining at most 0.29 hydroxyl groups per anhydroglucose unit in thecellulose molecule thereof, there being present in said textile materialat least one isolated non-conjugated aliphatic carbon-to-carbonunsaturation per 50 anhydroglucose units for protecting said dye againstO-fading, said dye being highly resistant to gas fading as indicated bynegligible fading when applied in the amount of 0.3% based on the fabricweight and in the absence of a gas-fading amass 10 a inhibitor to atextile fabric of cellulose triacetate hav ing an acetyl value of 61.5%by weight calculated as acetic acid and subjected to 3 units ofgas-fading exposure in accordance with Test Method 23-52 of the AmericanAssociation of Textile Chemists and Colorists.

3. A heat-treated textile material exhibiting a safeironing temperatureof at least 220 C. and having a basis of organic acid esterifiedcellulose containing at most 0.29 hydroxyl groups per anhydroglucoseunit in the cellulose molecule thereof, at least one oxygen atom per 50anhydroglucose units of the cellulosemolecule being bound to a radicalcontaining an isolated nonconjugated aliphatic carbon-to-carbonunsaturation for protecting said textile material against O-fading whensaid material is colored with an anthraquinone dye.

4. A heat-treated textile material exhibiting a safe ironing temperatureof at least 220 C. and having a basis of cellulose acetate crotonatecontaining at most 0.29 hydroxyl groups per anhydroglucose unit in thecellulose molecule thereof, there being present at least one crotonylgroup per 50 anhydroglucose units for protecting said textile materialagainst O-fading when said material is colored with an anthraquinonedye.

5. A textile material having a basis of an organic acid ester ofcellulose and having incorporated therein a minor amount of compatiblecompound free of basic nitrogen groups and having isolated aliphaticnon-conjugated carbon-to-carbon unsaturation for protecting said textilematerial against O-fading when said material is colored with ananthraquinone dyestulf.

6. A textile material having as basis of a cellulose organic acid estercontaining at most 0.29 hydroxy groups per anhydroglucose unit in thecellulose molecule thereof, said cellulose ester having incorporatedtherein a minor amount of a compatible compound free of salt-forminggroups and having isolated non-conjugated aliphatic carbon-to-carbonunsaturation for protecting said textile material against O-fading whensaid material is colored with an anthraquinone dye, said compoundselected from the group consisting of diallyl phthalate, diallylsuccinate, acrylic esters of monohydric and polyhydric alcohols,crotonic esters of monohydric and polyhydric alcohols, unsaturatedpolyesters of polyhydric alcohols and polycarboxylic acids, unsaturatedcellulose esters, unsaturated hydrocarbons, unsaturated ethers andunsaturated acetals.

7. A textile material having a basis of cellulose acetate containing atmost 0.29 hydroxyl groups per anhydroglucose unit in the cellulosemolecule thereof, said cellulose acetate having incorporated therein anunsaturated compound free of basic nitrogen groups and containing aplurality of isolated non-conjugated aliphatic carbonto-carbonunsaturations.

8. A textile material as set forth in claim 7, in which the unsaturatedcompound is polymeric and has a molecular weight of at least about 500.

9. A textile material as set forth in claim 8, in which theunsaturations are present in short chains pendant to the main chain ofthe polymer.

10. A textile material as set forth in claim 7, in which saidunsaturated compound is a linear polyester having a molecular weight ofat least about 500.

11. A textile material as set forth in claim 7, in which the unsaturatedcompound is a hydrocarbon polymer.

12. A textile material as set forth in claim 7, in which the unsaturatedcompound is a cellulose derivative selected from the group consisting ofethers and esters having isolated non-conjugated aliphaticcarbon-to-carbon unsaturation, said derivative being present in anamount ranging from about 1 to 1 0% by weight of the cellulose acetateand including suflicient unsaturations to provide at least oneunsaturation for each 50 anhydroglucose units of the cellulose acetate.

13. A textile material as set forth in claim 5, colored with ananthraquinone dye.

14 Process which comprises heat-treating a dyed textile material havinga basis of a cellulose organic acid ester containing at most 0.29hydroxyl groups per anhydroglucose unit in the cellulose moleculethereof, said cellulose ester having incorporated therein ananthraquinone dye and a minor amount of a compatible compound havingisolated non-conjugated aliphatic carbonto-carbon unsaturation freeof'salt-forming groups and for protecting said dyed material a gainstO-fading.

15. A spinning solution comprising a solution in a solvent comprisingmethylene chloride, of a cellulose acetate having an acetyl value of atleast 61%, calculated as combined acetic acid and, as an inhibitor ofO-fading, a minor amount of a compound free of salt-forming groups andhaving isolated non-conjugated aliphatic carbon te-carbon unsaturation.

References Cited in the file of this patent UNITED STATES PATENTSConciatori et al. June 30, 1959 OTHER REFERENCES The TextileManufacturer, February l955, pages 71 and 72. v

Billmeyer: Textbook of Polymer Chemistry," Interscience Publisher Inc.,N.Y., 1957, page 196.

14. PROCESS WHICH COMPRISES HEAT-TREATING A DYED TEXTILE MATERIAL HAVING A BASIS OF A CELLULOSE ORGANIC ACID ESTER CONTAINING AT MOST 0.29 HYDROXYL GROUPS PER ANHYDROGLUCOSE UNIT IN THE CELLULOSE MOLECULE THEREOF, SAID CELLULOSE ESTER HAVING INCORPORATED THEREIN AN ANTHRAQUINONE DYE AND A MINOR AMOUNT OF A COMPATIBLE COMPOUND HAVING ISOLATED NON-CONJUGATED ALIPHATIC CARBONTO-CARBON UNSATURATION FREE OF SALT-FORMING GROUPS AND FOR PROTECTING SAID DYED MATERIAL AGAINST O-FADING. 